If I borrow $1000 from you at 5% interest per year, after 1 year I will have to pay you $1000 plus 5% of $1000. Now, 5% means 5/100, so 5% of $1000 is 5/100 times 1000, which is 5 times 1000/100 which is 5 times 10 = $50. So after 1 year I would have to pay you back $1000 plus $50, which is $1050.

After 2 years, I would have to pay you $1000 plus $50 for the 1st year plus $50 for the 2nd year, which would be $1100.

So the interest I owe you would be the loan amount ($1000) times the interest rate (5%, or 5/100) times the time (2 years).

In your problem, we know the interest, the interest rate, and the time. So we would say that the interest ($360) is equal to the loan amount (unknown) times the interest rate (2%, or 2/100) times the time (3 years). At this point, we have to do a little algebra:

360 = 2 * 3 * x / 100

The opposite of dividing by 100 is multiplying by 100, so

360 * 100 = 2 * 3 * x,

36000 = 6x (divide both sides by 6)

x = 6000.

The student borrowed $6000 from his father and bought a very reliable, cheap used car, or maybe a fancy, but not very dependable pre-owned car!